1. Field of the Invention
The present invention relates to a cleaning machine having a constant head device.
2. Background Information
It is known to have floor cleaning units that have a liquid distribution system for dispensing detergent to wash the floor and/or clean water to rinse the floor. Often when washing the floor, detergent from one supply tank is automatically mixed with clean water and then the mixed cleaning solution is distributed on the floor. It is desirable to maintain a constant mix ratio between the detergent and clean water, especially in a gravity flow system for its low cost benefits. However, as the level of the water and detergent lowers during the application of cleaning solution in a gravity flow system, the flow rates out of the tanks will also decline and at disproportional rates from each other. This is due to the different static heads caused by the different levels of water and detergent in their respective tanks. These variable flow rates produces a variable mixing ratio. One solution is to pump the fluids from their respective tanks at a pressure that is much higher than the static head, thus making the effect of the liquid level on flow rate insignificant. However, the pump is an added cost, consumes power, and is subject to failure.
Another problem is that if the fluid levels in the tanks are unequal, cross flow occurs through the mixing chamber in which the output lines of the tanks are fluidly connected thereto. This cross flow results in uncontrollable mixing of the two fluids. One solution is to provide check valves in the output lines of the water and detergent tanks. However, this adds costs and causes flow restrictions to the system.
Hence, it is an object the present invention to provide a cleaning machine having a solution tank in which the flow of cleaning solution is constant irrespective of the level of cleaning solution.
It is another object of the present invention to provide a cleaning machine with clean water and detergent tanks having a low cost and reliable automatic mixing system in which the mixing ratio of clean water and detergent is constant irrespective of the levels of clean water and detergent in their respective tanks.